Possible constant assignment operators ":=" and "::=" for Python

[Fredrik Lundh]

tsaar2003 at yahoo.com wrote:

> For example:
>
> >>> A = []  # let's declare a "constant" here
> >>> b = A   # and let's assign the constant here
> >>> b.append('1') # OOPS!
> >>> c = A
> >>> print A
> ['1']
> >>> print b
> ['1']
> >>> print c
> ['1']
>
> As you can see, the "constant" A can be modified this easily. But if
> there were an intuitive mechanism to declare a symbol to be immutable,
> then there won't be this problem.

why are you using mutable objects as constants?

(insert obligatory "it hurts when I do this" joke here)

btw, given a hypothetical "object that symbol points to is immutable" syntax,
what would you expect this to do ?

    >>> constant A = []

    >>> b = [A]

    >>> # much later
    >>> b[0].append('1')

</F>